Collection Types - C# Dictionary and Hashtable

Differences Between Hashtable and Dictionary

The System.Collections.Hashtable class, and the System.Collections.Generic.Dictionary<TKey, TValue> implements the System.Collections.IDictionary interface. The Dictionary<TKey, TValue> generic class also implements the IDictionary<TKey, TValue> generic interface. Therefore, each element in these collections is a key-and-value pair.

In this article I will share the difference between C# Dictionary and Hashtable with example and how to decide which one to use?

C# Hashtable

• Hashtable is not a generic type.
• All the members in a Hashtable are thread safe.
• It is slower than dictionary because it requires Boxing and Unboxing.
• It returns null if we try to find a key which does not exist.

C# Code Examples

private void HashtableSample()

        {

            // Inserting values into C# Hashtable

            Hashtable objHash = new Hashtable();

            objHash.Add(1, 100); // using int datatype

            objHash.Add(2.99, 200); // using float datatype

            objHash.Add('A', 300); // using char datatype

            objHash.Add("AB45", 500); // using string datatype

            //c# Hashtable getting values by Key name

            lblText.Text = objHash[1].ToString();

            lblText.Text = objHash[2.99].ToString();

            lblText.Text = objHash['A'].ToString();

            lblText.Text = objHash["AB45"].ToString();

        }

C# Dictionary

• Dictionary is a generic type which means we use it with any data type.
• Only public static members are thread safe.
• It is faster than a Hashtable because there is no Boxing and Unboxing.
• It returns an error if we try to find a key which doesn't exist.

C# Dictionary Examples

private void DictionarySample()

        {

            // Inserting values into C# Dictionary

            Dictionary<string, int> dic = new Dictionary<string, int>();

            dic.Add("Rk", 1);

            dic.Add("Sk", 5);

            dic.Add("Kv", 8);

            // Getting dictionary key by value

            foreach (KeyValuePair<string, int> pair in dic)

            {

                lblText.Text = pair.Key + " = " + pair.Value + " " + lblText.Text;

            }

}

Conclusion: It was fun in learning and writing an article on Collection Types - C# Dictionary and Hashtable. I hope this article will be helpful for enthusiastic peoples who are eager to learn and implement some interesting stuffs in new technology. 

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